Small size crane having a hydraulically operated jib and an electromotor-driven hydraulic pump

ABSTRACT

An electromotor-driven small size crane comprises a rotary crane post presenting two spaced-apart sidewalls, a vertically swingable jib on said post and a hydraulic jack for actuating the jib, said jack normally occupying a forwardly inclined position relative to the crane post and including a cylinder having its rear end hingedly connected to the lower end portion of the crane post between said sidewalls thereof. An oil pump and an electromotor for driving the same are both mounted on the back of the cylinder so as to partake in the tilting movements of the latter during raising and lowering of the jib and so as to normally remain substantially sheltered between said sidewalls of the crane post. Preferably, said pump and motor are covered by a cap removably attached to the cylinder, which also carries an oil reservoir and valve means for operating the crane.

United States Patent I Karl Fritjof Torbjtirn Adolfsson 72 Inventor2,756,563 7/1956 Bohlman 60/52 us Bjorn Tradgflrdsgrand 3, Stockholm,3,078,961 2/1963 Powell l87/8.59 [21] A l N $322 1 FOREIGN PATENTS pp o.Filed g 1968 822,165 10/1959 Great Britain 60/52 US [45] Patented Sept.28, 1971 Primary Examiner-Harvey C. l-lomsby [32] Priority Aug. 30, 1967Attorny-Amold Robinson [33] Sweden 131] 12015/67 [54] SMALL SIZE CRANEHAVING A AllSTRACT: An electromotor-driven small size crane com-HYDRAULIC ALLY OPERATED m AND AN pllSS a [0131)! crane post presenting[W0 spaced-apart ELECTROMOTOR DRIVEN HYDRAULIC PUMP sidewalls, avertically swingable jib on said post and a hydrau- 2 Claims 2 Drawing[38$ lic jack for actuating the jib, said jack normally occupying aforwardly mclmed position relative to the crane post and in- [52] [1.5.CI. 212/35, eluding a cylinder having its rear end hingedly connected to21258, 60/52 212/ 55 the lower end portion of the crane post betweensaid sidewalls [51] Int. Cl. 1366c 23/54 h fl A n pump and anelectromomr for driving the Same [50] Field of Search 2.12/28, are bmounted on the back of the cylinder so as to partake 61; 60/52 Us in thetilting movements of the latter during raising and lower ing of the jiband so as to normally remain substantially shel- [56] Rderences cuedtered between said sidewalls of the crane post. Preferably, said UNITEDSTATES PATENTS pump and motor are covered by a cap removably attached to1,690,181 11/1928 Sederholm 60/52 US the cylinder, which also carries anoil reservoir and valve 2,517,813 8/1950 Wallace 212/35 l-lC means foroperating the crane.

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SMALL SIZE CRANE HAVING A HYDRAULICALLY OPERATED .118 AND ANELECTROMOTOR-DRIVEN HYDRAULIC PUMP This invention is concerned withsmall size cranes of the type comprising a rotary crane post, avertically swingable and, preferably, extensible jib mounted thereon, ahydraulic jack means to effect vertical swinging movements of the jiband a pump for supplying pressure fluidum to the hydraulic jack means,and wherein the crane post is formed with two spaced sidewall portionsalong a major part of its height and the hydraulic jack means includes apiston rod having its upper end hingedly connected to the jib and acylinder having its lower end hingedly connected to the crane postbetween said spaced sidewall portions thereof. Due to their relativelysmall size and weight these cranes are readily portable and usually theyare provided with a swivel pin projecting from the lower end of thecrane post and adapted to be removably fitted into a socket secured in abase at the site or on the vehicle where the crane is to be used.

in my prior US. Pat. No. 3,326,391 of June 20, 1967 there is disclosed asmall size rotary crane of substantially such character and presentingvaluable features which may, if desired, be applied also in combinationwith my present invention.

Small size rotary cranes of this type have found extensive use for thehandling of heavy objects, such as various loads, work pieces, buildingelements and the like, not only on trucks and other vehicles but also instorage rooms, workshops, loading yards, building sites and many otherplaces. As also appears from my said prior patent these cranes werepreviously commonly provided with a handor foot-actuated pump, if theywere not supposed to be specifically used, e.g. on a truck, where asuitable separate pressure fluidum source was already available andcould conveniently be used also for supplying the crane, which is, ofcourse, a rather rare condition. The operation of the cranes by means ofa handor foot-actuated pump is, however, rather slow and inconvenient.

Therefore, the cranes in question are nowadays frequently delivered withan electromotor-driven hydraulic pump, at least as a special andoptional equipment. Up to now the hydraulic pump and its relatedelectromotor have then usually been mounted as an additional unit on theoutside of one of the sidewall portions of the crane post proper. Withsuch an additional pump and motor unit forming a rather clumsy andspacious projection on the crane post, the cranes have, however, lost aconsiderable part of their valuable slendemess and adaptability, and thepump and motor unit is also highly exposed to damage by blows andimpacts. A further inconvenience with this known mounting of the pumpand electromotor unit on the crane is that flexible pressure fluidumconduits are required between the hydraulic pump and the cylinder of thehydraulic jack means, because the pump is then rigidly secured to thecrane post while the cylinder is, of course, swingably mounted inrelation to the same.

The object of the present invention is to eliminate these inconveniencesin cranes of the type referred to hereinbefore and having anelectromotor-driven fluidum pump. in accordance with the invention, thisis achieved by mounting both the hydraulic pump and its relatedelectromotor, the one above the other, relatively high up on the rearside of the cylinder forming part of the hydraulic jack means, i.e. onthe side of the said cylinder facing away from the outer end of the jib,so that the pump and the motor will not only partake in the tiltingmovements of the cylinder during during the raising and lowering of thejib but also become substantially sheltered between the said spacedsidewall portions of the crane post, when the jib is in operativeposition.

As well known, the hydraulic jack means, including the cylinder, willoccupy a forwardly inclined position during the normal operation of thecrane jib and this is essential in connection with the invention, sincethe space between the two sidewall portions of the upright crane post isthen free for taking up the pump and motor unit. The fact that the unitcould then possibly partly project beyond the back side of the cranepost in such cases, where the jib may be, and is, swung down into aninoperative position substantially parallel with the front side of thecrane post, is generally of no importance since the crane need not thenbe operated by an operator and is commonly not exposed to the same riskof being damaged either.

For further elucidation of the invention a preferred embodiment thereofwill be more closely described in the following, reference being hadtherein to the accompanying drawing, wherein FIG. 1 is a side view of arotary small size crane embodying the invention, the one sidewallportion of the crane post being partly removed to show the parts insideit and the jib occupying a substantially horizontal, operative position,and

FIG. 2 is a rear view of the same crane, i.e. is showing the crane fromthe left in FIG. 1.

The rotary hydraulic crane shown in the drawing consists primarily of acrane post, generally designated by l, which is rotatable about avertical swivel pin 2 projecting from the lower end of the post andadapted to be received in a fitting socket 3 secured in a support orbase 4, which may be stationary or movable. At the upper end of thecrane post there is, by means of a traversing pivot pin 5, mounted avertically swingable jib 6, which is provided with a telescopicextension 6' having at its outer end a hook 7 for the suspension of theload. On the underside of the jib 6 there is an attachment or ear 8 towhich the upper end of a piston rod 9 is hingedly connected. The pistonrod 9 forms part of a hydraulic jack means also including a cylinder 10,the lower end of which is hingedly connected to the crane post 1 bymeans of a horizontal pivot pin 11.

As most clearly appears from FIG. 2 the crane post 1 is bifurcated alonga major part of its height and built up of two spaced-apart sidewallportions 12 and 13, both having inwardly turned side edges for improvedstrength. These sidewall portions are held together at their lower endsby means of a bottom plate 14, from the underside of which the swivelpin 2 is projecting, and also by means of a crosspiece 14, while theirupper ends are held together by the pivot pin 5 for the jib 6. There is,of course, nothing preventing the use of further interconnectionsbetween the two sidewall portions 12 and 13 of the crane post as long asthe same do not interfere with the hydraulic jack means and the jib,respectively. The cylinder 10 of the hydraulic jack means has its lowerend mounted between the two sidewall portions 12 and 13 of the cranepost 1 in such a manner that the entire jack means may be receivedwithin the crane post, when the jib is swung down into an inoperativeposition substantially parallel with and close to the front side of thecrane. With the jib in such inoperative position the crane will form arather compact and conveniently portable unit.

The crane as shown further comprises a hydraulic pump 15 with a relatedelectric driving motor 16, both of which are, in accordance with theinvention, mounted, the one above the other, relatively high up on therear side of the cylinder 10, i.e. the side thereof facing away from theouter end of the jib, so that they will partake in the tilting movementsof the hydraulic jack means during the raising and lowering of the jib.As shown, the pump 15 and the electromotor 16 are then suitably coveredby a detachable protective cap 17, which forms a kind of rucksack" onthe cylinder 10. Below the pump 15 on the cylinder 10 there is, in theexample shown, mounted an oil reservoir 18, which is preferably alsocovered by the cap 17, and further below the reservoir there is a valvehousing 19 accommodating the valves required for the operation of thepump and the hydraulic jack means. The valves are actuatable by means ofa lever 20 in FIG. 1, which may be alternatively connected to the oneend or the other of an actuating spindle 21 traversing the valve housing19, so that convenient actuation can take place from either side of thecrane. However, there is nothing to prevent the use of a modified typeof valve housing, in which actuation can take place from the rear sideof the crane, in which case the valve housing, of course, does not needto project so much beyond the back of the crane post.

As clearly appears from FIG. 1, the hydraulic pump 15 and itselectromotor 16 will become sheltered in a favorable manner between thesidewall portions 12 and 13 of the crane post during the normaloperation of the crane and at the same time, they will not in any wayinterfere with the swinging movements of the crane about the swivel pin2. Since the pump 15, the oil reservoir 18 and the valve housing 19 fonna rigid assembly with the cylinder 10, the conduit installation betweenthese components will, of course, become very simple and require noflexible hoses. Since the electromotor l6 and the pump 15 are bothrigidly mounted on the same support, that is the cylinder 10, there isalso no need for flexible power transmission means between them. At thesame time, all the components of the hydraulic system including thecylinder and the pump motor will form a self-contained unit which caneasily be exchanged when ever necessary. Electric current is preferablysupplied to the motor 16 from a battery or a main net through anelectric cable 22. The hydraulic pump 15 and the electric motor 16 can,of course, be of any suitable type, provided that they are sufficientlysmall in size to enter the free space between the sidewall portions ofthe crane post.

l claim:

1. A crane comprising a crane post formed with two spacedapart sidewallportions along a major part of its height; a vertically swingable jibhaving its inner end portion hingedly connected to the top of the cranepost and extending away therefrom when in operative position; hydraulicjack means to effect vertical swinging movement of the jib and includinga cylinder having its rear end hingedly connected to the lower endportion of the crane post between said two spaced apart sidewallportions thereof, said cylinder having a diameter less than the spacebetween said sidewall portions to permit said cylinder to swing betweensaid sidewall portions, and a ram extending from said cylinder andhaving its outer end hingedly connected to the jib in a manner causingsaid cylinder and ram to occupy a forwardly inclined position when thejib is in operative position; an oil reservoir mounted on said cylinder;an oil pump for delivering oil under pressure from said reservoir;actuatable valve means mounted on said cylinder for controlling the flowof oil from said pump into said cylinder and from said cylinder back tothe reservoir, respectively; and an electric motor operable to drivesaid oil pump; said electric motor and oil pump being both mounted, oneabove the other, on the rear side of said cylinder facing away from theouter end of the jib and being of a combined length no greater than thelength of said cylinder, each having a diameter substantially equal tothe diameter of said cylinder, such that said electric motor and pumpswing with said cylinder between said sidewall portions during theraising and lowering of the jib and said electric motor and pump aredisposed to be substantially sheltered between said spaced-apartsidewall portions of the crane post when the jib is in operativeposition.

2. A crane according to claim 1 further comprising a protective capremovably attached to said cylinder in a manner to cover said electricmotor and oil pump.

1. A crane comprising a crane post formed with two spaced-apart sidewallportions along a major part of its height; a vertically swingable jibhaving its inner end portion hingedly connected to the top of the cranepost and extending away therefrom when in operative position; hydraulicjack means to effect vertical swinging movement of the jib and includinga cylinder having its rear end hingedly connected to the lower endportion of the crane post between said two spaced apart sidewallportions thereof, said cylinder having a diameter less than the spacebetween said sidewall portions to permit said cylinder to swing betweensaid sidewall portions, and a ram extending from said cylinder andhaving its outer end hingedly connected to the jib in a manner causingsaid cylinder and ram to occupy a forwardly inclined position when thejib is in operative position; an oil reservoir mounted on said cylinder;an oil pump for delivering oil under pressure from said reservoir;actuatable valve means mounted on said cylinder for controlling the flowof oil from said pump into said cylinder and from said cylinder back tothe reservoir, respectively; and an electric motor operable to drivesaid oil pump; said electric motor and oil pump being both mounted, oneabove the other, on the rear side of said cylinder facing away from theouter end of the jib and being of a combined length no greater than thelength of said cylinder, each having a diameter substantially equal tothe diameter of said cylinder, such that said electric motor and pumpswing with said cylinder between said sidewall portions during theraising and lowering of the jib and said electric motor and pump aredisposed to be substantially sheltered between said spaced-apartsidewall portions of the crane post when the jib is in operativeposition.
 2. A crane according to claim 1 further comprising aprotective cap removably attached to said cylinder in a manner to coversaid electric motor and oil pump.